Osama wanted a Muslim source on honor killings. How about this one:
Sunan Ibn Majah 2540—It was narrated from Ubadah bin Samit that the Messenger of Allah said: “Carry out the legal punishments on relatives and strangers, and do not let the fear of blame stop you from carrying out the command of Allah.”
Here Muslims are told to carry out Islamic punishments against their own families. So if a daughter is behaving immorally, the family is to carry out the punishment. Any questions?
It's strange that a man who said he would skin his own sister alive if she became "loose and flirty" is challenging honor killings.